Fluoride flaws

The government is poised to reignite one of the most vexed medical issues of the past 50 years. Early next month, parliament will debate clauses of the water bill which will give indemnity against legal action to water companies that add fluoride to their supplies, paving the way for the extension of fluoridation schemes throughout this country.

Fluoridation is the addition of silicofluorides (hexafluorosilicic acid or, less commonly, sodium hexafluorosilicate) at the level of one part per million to public water supplies. The adversaries could not be more starkly opposed. Proponents believe that fluoridation brings about a reduction of caries in children’s teeth, and that this is especially beneficial for children in socially deprived areas. They insist that there are no detrimental public health consequences, whether short- or long-term. Opponents argue that silicofluorides are a class 2 poison under the Poisons Act, have serious adverse health effects, and in any case do nothing to benefit children’s teeth.

Fluoridation schemes were first introduced in the United States in 1946. Since the late 1960s, about 10% of the UK population has received fluoridated water supplies – primarily, those in areas served by the Severn Trent, Northumbrian and Anglian water companies. During the postwar decades, the benefits of fluoride were held to be incontestable as dental health rapidly improved. However, with better diet and treatment, it was improving across the western world. As far back as 1986, Nature published an article showing that rates of tooth decay were coming down as quickly in unfluoridated communities as in fluoridated ones.

More recent studies published in 2000-01 of communities in Finland, Cuba, Canada and east Germany, which abandoned fluoridation, found that rates of dental decay did not rise (and, indeed, continued to decline) afterwards. The city of Basle in Switzerland recently stopped fluoridation, partly because there was no evidence that rates of tooth decay were lower there than in non-fluoridated Swiss cities. In Western Europe, only England, Ireland and a tiny part of Spain retain fluoridation programmes.

In December 2002, four members of the government’s last major study of the effects of water fluoridation (the York review, published September 2000) – Professor Jos Kleijnen and Professor Trevor Sheldon of York University, Professor George Davey-Smith of Bristol University and Sir Iain Chalmers of the Cochrane Centre – wrote to Hazel Blears, the public health minister, about the effectiveness of fluoridation in reducing caries: “We could discover no reliable, good quality evidence in the fluoridation literature worldwide. What we found suggested that fluoridation was likely to have a beneficial effect, but in fact the range could be anywhere from a substantial benefit to a slight disbenefit to children’s teeth.”

The prime area of international controversy surrounds fluoride’s possible adverse health effects. According to the British Fluoridation Society, one of the ways in which fluoride is supposed to work is by “inhibiting the function of enzymes” which cause the build-up of acid that leads to tooth decay.

However, it seems scientifically illogical that fluoride would inhibit some enzymes but not others. Moreover, it is known that fluoride accumulates in calcifying tissue, such as teeth and bones. The pineal gland in the brain (where seratonin and melatonin are produced) is a calcifying tissue. Research by Dr Jennifer Luke established that fluoride accumulated to high levels in the pineal gland. In animal studies, she showed that this led to the reduced production of melatonin (because the fluoride inhibited the enzymes needed to produce it), and that, in turn, caused the earlier onset of puberty. This work dovetailed with studies which have shown that girls in the US – the world’s most heavily fluoridated country – are reaching puberty earlier and earlier.

There are also concerns about fluoride’s effect on the thyroid gland. The thyroid regulates body temperature and energy levels. It needs iodine to function properly, yet iodine will be displaced by fluorides. Hypothyroidism (an under-active thyroid) is a significant and growing problem in the US.

Earlier this month, Sam Epstein, the chairman of the Cancer Prevention Coalition and professor emeritus of environmental and occupational medicine at the University of Illinois, pointed to the epidemiological studies linking fluoride and bone cancer, and said that “the imposition of fluoridation on the UK public [would] present a significant public health hazard”.

Other studies have linked fluoride with higher incidences of miscarriages and Down’s syndrome births, and decreased IQ levels.

Those already affected by dietary deficiencies, who are low in calcium, magnesium and essential nutrients – in other words the poor and those in ill-health – will be more vulnerable to fluoride toxicity. For this reason, opponents of fluoridation argue that it should certainly not be considered in inner-city areas.

Perhaps the main finding to emerge from the York review was the weakness of the research base: “Little high quality research has been undertaken in the area of fluoride and health.” One would have expected the government to remedy this before legislating to put fluoride into the country’s public water supplies.